!== is in there, but how should 
"(",")" and "{","}" and <<< HERE DOCS
fit in there ?

() has the highest precedence, eg.
$a = 1 && $b = 2;
($a = 1) && ($b = 3);
It was a bug report that made me thinking it should be added.

{} well, I don?t know why it works, but it works like []
echo $x{1}='test2';
var_dump($x); // results in an arry

!== you?re right, did not see

<<< well and here-docs seem to have the hightest precedence
too, similar to new

$x=1;
$a=1;
$x=!$a=<<<test
0
test;
echo $x;
echo $x;

note: andi mentioned, that {} should *not* be used to access
array elements.

Here docs are in the manual.